In the allowed Goode et al. U.S. application Ser. No. 08/077,242, filed Jun. 14, 1993 now U.S. Pat. No. 5,350,363 and entitled Enhanced Sheath Valve, a partition valve for a catheter sheath introducer is disclosed having rotating radial slits extending completely through the elastomeric partition valve in a manner similar to Hillstead U.S. Pat. No. 4,895,565. Such slit elastomer medical instrument valves are placed on the proximal end of a catheter sheath introducer, for example, to permit the introduction of a catheter or guidewire into the arterial system of a patient while preventing back bleeding through the proximal end of the catheter sheath introducer, even when a catheter or guidewire is present.
One problem that is found in the present conventional catheter sheath introducers is that after a catheter has been introduced to the arterial system of a patient through the catheter sheath introducer and withdrawn, difficulties may be encountered with the valve in terms of suppression of bleeding if a guidewire is subsequently advanced through the partition valve, since the guidewire is so much smaller than the initial catheter that extended therethrough. This may happen because the catheter may cause some tearing in the slits of the valve. Also, the various flaps of the valve as defined by the slits may not fold together in their proper, original manner. Also, the subsequently applied guidewire may fail to be centered in the valve, which can result in an amount of back bleeding through the valve.
Also, as another technical problem, the elastomers of the Goode et al. application have high elongations, generally being at least 900 percent and more. Such elastomers exhibit a relatively low cross-link density, being tacky and exhibiting an amount of flow resulting from this low cross-link density. Thus, upon storage, it has been found that slits cut out of such elastomers may actually disappear through resealing across the slits, so that they cease to be of optimum use as penetratable seals in a catheter sheath introducer or the like.
By this invention, improvements are provided in which the resealing capability of elastomer valve partitions may be improved, both with respect to the prevention of the resealing of precut slits through the valve partitions. The invention also provides a new valve partition which facilitates the centering of guidewires extending through the partition, while also facilitating the resealing of the valve partition to minimize backbleeding during use. Such a valve partition better tolerates the passage of a larger diameter catheter, followed by a smaller diameter guidewire without exhibiting the previous disadvantage of tearing or substantially leaking blood.